An exhaust system conducts hot exhaust gases generated by an engine through various exhaust components to reduce emissions and control noise. The heat energy contained in exhaust gases represents almost a third of the energy contained in the fuel. An exhaust heat recovery system (EHRS) is used to transfer this energy to another vehicle device or to a fluid, such as a coolant liquid for example. The EHRS includes a valve that is positioned within an exhaust system component to control exhaust flow into a heat exchanger.
Traditional exhaust systems also include acoustic valves that are used for noise attenuation purposes. Often multiple acoustic valves are required, dependent upon the type of vehicle application, to address specific ranges of noise such as low and high frequency noises. The incorporation of multiple valves for noise control and the EHRS significantly increases the cost of the exhaust system.